Syngas

Syngas (from synthesis gas [SNG]) is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen, and very often some carbon dioxide, to use for energy. Examples of production methods include the gasification of coal, as well as steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, biomass, and in some types of waste-to-energy gasification facilities. It typically has less than half the energy density of natural gas.

Coal gasification involves the conversion of coal into electricity, hydrogen, and other energy products. Gasification is a thermo-chemical process that breaks down coal - or virtually any carbon-based source - into its basic chemical constituents. In a modern gasifier, coal is typically exposed to steam and carefully controlled amounts of air or oxygen under high temperatures and pressures. Under these conditions, molecules in coal break apart, initiating chemical reactions that produce a mixture of carbon monoxide, hydrogen, and other gaseous compounds such as carbon dioxide.

Commercial Use
For a List of IGCC Plants, go to Integrated Gasification Combined Cycle (IGCC) For a List of Proposed and Canceled Coal-to-Liquid Plants, go to Coal-to-Liquids

Coal gasification electric power plants are now operating commercially in the United States and in other nations, and the U.S. Department of Energy states that "many experts predict that coal gasification will be at the heart of future generations of clean coal technology plants", such as Integrated Gasification Combined Cycle (IGCC) plants.

Benefits
Coal companies argue the benefits of gasification stem from the capability to achieve lower sulfur dioxide, nitrous oxide, and particulate emissions than conventional coal burning, increased fuel efficiency, and carbon dioxide emissions that are potentially easier to trap and store than conventional coal burning plants, should carbon capture and storage technologies prove feasible.

Problems
Although potentially lowering the amount of some pollutants, the health and environmental problems with coal plants remain, such as the coal waste byproducts of coal mining and burning (toxins and pollutants from coal waste, coal ash, and coal sludge), the environmentally destructive effects of coal mining, particularly mountaintop removal, and increased carbon dioxide emissions, the main cause of human-influenced global warming.

Greenhouse gas emissions
Liquid coal production emits about twice as much global warming pollution as gasoline and requires at least four gallons of water per gallon of fuel produced.

A study released in October 2008 found that if the United States tried relying on gasoline made from domestic coal as a means of achieving independence from foreign oil, the result would likely be an increase in carbon emissions. The researchers concluded that greenhouse gas emissions could actually almost double if natural gas or domestic coal were to replace foreign oil. Even if all potential means of reducing emissions were used, including any future development of carbon capture and storage technologies, the alternative fuels would not provide any reduction in greenhouse gas emissions.

Proposed US Senate tax subsidies
On December 10, 2010, the National Wildlife Federation learned the Senate version of tax legislation includes subsidies for liquid coal fuels. Section 704 of the Senate tax bill as written would extend the Alternative Fuel Tax Credit to liquid coal, giving a 50-cent tax credit for each gallon of liquid coal sold or used in a fuel mixture. The provision could cost taxpayers an estimated $400 million per plant, every year.

Related SourceWatch articles

 * Coal-to-Liquids
 * Integrated Gasification Combined Cycle (IGCC)
 * Clean Coal
 * Carbon capture and storage
 * Proposed Synfuels Plants in the United States
 * Underground Coal Gasification

External resources

 * Daniel C. Cicero, "Coal-to-Liquids in the United States, Status and Roadmap," National Energy Technology Laboratory, June 23-24, 2008